1.4 Source Code Analysis

1.4.1 SEARCH

Endpoints & URL-matching patterns

grep -Ei 'api' -Ei 'http' -Ei 'https' -Ei 'URI' -Ei 'URL' -R .

grep -Eio '(http|https)://[^/"]+' -Eio 'content://[^/"]+' -R .

Files & their permissions

grep -Ei 'MODE_WORLD_READABLE' -Ei 'MODE_WORLD_WRITEABLE' -R .

grep -Ei 'getCacheDir' -Ei 'getExternalCacheDirs' -R .

grep -Ei 'openFileOutput' -Ei 'FileOutputStream' -Ei 'OutputStream' -Ei 'getExternalFilesDir' -R .

Database & realms

grep -Ei 'localUserSecretStore' -Ei 'getWriteableDatabase' -Ei 'getReadableDatabase' -R .

grep -Ei 'realm' -Ei 'getDefaultInstance' -Ei 'beginTransaction' -Ei -R .

grep -Ei 'SQLiteDatabase' -Ei 'insert' -Ei 'query' -Ei 'delete' -Ei 'update' -R .

User

grep -Ei 'username' -Ei 'user' -Ei 'pass' -Ei 'passwd' -Ei 'userid' -Ei 'password' -R .

grep -Ei '.config' -Ei 'secret' -Ei 'token' -Ei 'login' -Ei 'auth' -R .

Logs

grep -Ei 'Log.v' -Ei 'Log.d' -Ei 'Log.i' -Ei 'Log.w' -Ei 'Log.e' -R .

grep -Ei 'log' -Ei 'logger' -Ei 'printStackTrace' -Ei 'System.out.print' -Ei 'System.err.print' -R .

Content

grep -Ei 'Cursor' -Ei 'content' -Ei 'ContentResolver' -Ei 'CONTENT_URI' -Ei 'Loader' -Ei 'onCreateLoader' -Ei 'LoaderManager' -Ei -R . 

Keystore

grep -Ei 'AndroidKeystore' -Ei 'KeyStore' -Ei 'crypto' -Ei 'cipher' -Ei 'store' -R .

1.4.2 OPEN SOURCE FILES

jd-gui app-dex2jar.jar

• opens .jar/.java/.class files

• or use an IDE of your choice (android studio or eclipse)

1.4.3 INFO

INTERESTING CLASSES

• SharedPreferences (stores key-value pairs)

• FileOutPutStream (uses internal or external storage)

INTERESTING FUNCTIONS

• getExternal* (uses external storage)

• getWriteableDatabase (returns SQLiteDB for writing)

• getReadableDatabase (returns SQLiteDB for reading)

• getCacheDir / getExternalCacheDirs (uses cached files)

1.4.4 THINGS TO REPORT

• Cleartext credentials (includes base64 encoded or weak encrypted ones)

• Credentials cracked (brute-force, guessing, decrypted with stored cryptographic-key, a.s.o...)

• File permission MODE_WORLD_READABLE / MODE_WORLD_WRITEABLE (other apps/users are able to read/write)

• If http is in use (no SSL)

• Anything that shouldn't be there (debug info, comments with info disclosure, ...)